• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.4
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• pp.285-291
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• 2015

In this paper, we propose a classification algorithm for postures of sitting person by using IMU(inertial measurement unit). This algorithm uses PCA(principle component analysis) for decreasing the number of feature vectors to three and SVM(support vector machine) with RBF(radial basis function) kernel for classifying posture types. In order to collect the data, we designed neckband-shaped earphones with IMU, and applied it to three subjects who are healthy adults. Subjects were experimented three sitting postures, which are neutral posture, smartphoning, and writing. As the result, our PCA-SVM algorithm showed 95% confidence while the dimension of the feature vectors was reduced to 25%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.115-117
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• 2013

수평자세제어에 대한 활용은 다양한 진동이 발생하는 환경에서 정확한 수평제어를 필요로 하는 모든 분야에 활용할 수 있다. 이러한 수평제어에 대한 문제는 다수의 액추에이터(Actuator)를 어떠한 방법으로 제어하는가에 따라 그 성능이 달라지며, 발생한 외란에 대하여 어떠한 방법으로 외란을 계측하고 특성을 분석하는 것이 무엇보다 중요하다. 이러한 비선형성이 강한 수평자세제어에 대하여 인공지능기법인 신경회로망의 학습기능을 활용하여 그 수평자세 제어에 대한 성능을 연구하고 있는 추세에 있다. 본 논문에서는 고속이며 신뢰성을 보장하고 있는 CAN 통신방식을 활용하여 3개의 리니어 액추에이터(Linear Actuator)를 동시에 제어하도록 하고, 플랜트의 기울어진 상태는 자이로센서를 활용하여 플랜트의 상태를 지능적으로 판단하게 하였다. 또한 플랜트에 발행하는 왜란은 수평자세제어를 위한 플랜트 위에 볼(ball)을 놓아 비선형적인 왜란이 발생하도록 하였다. 이러한 왜란에 대하여 영상처리 기법을 활용하여 지능적으로 제어하도록 하여 CAN 통신의 활용성과 영상처리시스템(Image Processing System)의 활용성 및 지능제어의 활용성을 제시하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.860-862
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• 2018

오늘날, 현대인들의 생활 속에서 스마트폰을 빼놓을 수 없을 만큼 스마트폰을 장시간 이용하는 사람들이 많다. 스마트폰 이용시간이 늘어날수록 목을 숙인 자세를 유지하게 되며, 이는 VDT 증후군 중 거북목증후군을 발생시킬 가능성이 높다. 본 논문에서는 사용자의 목 각도를 유추해 거북목 자세가 일정시간 유지될 때 알림기능을 제공하는 애플리케이션을 개발하였다. 애플리케이션을 통해 스마트폰 사용자들이 자신의 자세를 인지하고 올바른 자세로 교정할 수 있도록 유도하였다. 본 애플리케이션은 스마트폰의 기울기에 따라 사용자의 목각도를 추측하기 때문에, 스마트폰의 기울기와 목각도간의 상관성 분석 실험을 수행하여 애플리케이션의 유효성을 입증하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.179-182
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• 2011

A practical application of flight-axes/attitude control thrusters to the space launch vehicle and their design development localization are investigated and analyzed. Hydrazine thrusters are mostly used in a final stage of space launch vehicles on account of its higher specific impulse and reliability necessary for the precise attitude control attaining the orbit insertion with higher accuracy.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.295-302
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• 2013

Many reported methods assume that the people in an image or an image sequence have been identified and localization. People detection is one of very important variable to affect for the system's performance as the basis technology about the detection of other objects and interacting with people and computers, motion recognition. In this paper, we present an efficient linear discriminant for multi-view people detection. Our approaches are based on linear discriminant. We define training data with fisher Linear discriminant to efficient learning method. People detection is considerably difficult because it will be influenced by poses of people and changes in illumination. This idea can solve the multi-view scale and people detection problem quickly and efficiently, which fits for detecting people automatically. In this paper, we extract people using fisher linear discriminant that is hierarchical models invariant pose and background. We estimation the pose in detected people. The purpose of this paper is to classify people and non-people using fisher linear discriminant.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.191-199
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• 2008

The purpose of this study was to analyze movement of inline skate players at inline roller skate T300m start so that we can find effective starting movement, and provide basic and scientific materials in improving performance of inline roller skaters for T300m inline roller skating. In doing so, five Korean national representative inline skaters who elected in 2008 Korean National Inline Roller Skating Cup were taped during the cup and analyzed through 3D viewing in terms of their starting movement Conclusions of the analysis were as follows: First, the better the record of starting phase is the shorter average of contact time on track. Second, to improve starting speed, players raised their body just like running instead of lowering them when gliding. players could shorten their strike and moved faster in order to accelerate, and it was more effective to speed up when they quickly switched from running to gliding. Third, the five country-representative players speeded up by bending their knees to a greater degree in order to improve stability. And then the most effective way was believed to minimize track connection of skating at starting in each phase.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.799-804
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• 2015

The purpose of this study is to analyse the dynamic disturbances(disturbed forces and disturbed torques) due to attitude control thruster's plume impingement on the solar arrays. To produce database of the dynamic disturbances a sweep analysis was done, in which the two parameters are used; the distance between the thruster and solar arrays and the thruster tilt angle. Based on the database, a third order polynomial approximation is computed to represent the characteristics of the disturbed forces and torques. The final results are the coefficients of the approximation for each solar array angle position. These results as input data are used to optimize the configuration of the attitude control thrusters. This analysis is appled to the two candidate solar arrays for Geo-Kompsat-2 satellite and the results of the disturbed forces and disturbed torques are compared and analysed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.2
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• pp.137-145
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• 2005

In this paper, we investigate the accuracy of various sensor models developed for linear pushbroom satellite images. We define the accuracy of a sensor model in two aspects: the accuracy of bundle adjustments and the accuracy of estimating exterior orientation parameters. The first accuracy has been analyzed and reported frequently whereas the second accuracy has somewhat been neglected. We argue that the second accuracy is as important as the first one. The second accuracy describes a model's ability to predict satellite orbit and attitude, which has many direct and indirect applications. Analysis was carried out on the traditional collinearity-based sensor models and orbit-based sensor models. Collinearity-based models were originally developed for aerial photos and modified for linear pushbroom-type satellite images. Orbit-based models have been used within satellite communities for satellite control and orbit determination. Models were tested with two Kompsat-1 EOC scenes and GPS-driven control points. Test results showed that orbit-based models produced better estimation of exterior orientation parameters while maintained comparable accuracy on bundle adjustments.

• Korean Security Journal
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• no.19
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• pp.207-223
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• 2009

The main purpose of this study was to analyze the reaction time of body guards in different stances to provide quantification of data for educational use. There were 4 martial art trained body guards participating in this study. The results of the EMG analysis and reaction time are as follows. The average reaction time of the whole body was $1.38{\pm}0.07$ seconds. In the first phase the reaction to the signal was $0.22{\pm}0.02$ seconds while in the second phase the reaction after checking was $0.62{\pm}0.10$ seconds, which produced the largest impulse. the reaction times of the third and fourth phase were gradually reduced, $0.29{\pm}0.02$ seconds and $0.26{\pm}0.02$ seconds consecutively. In the body guard posture the following muscles had a high activity level; phase one the right and left of the tibialis anterior muscle, phase two the right and left of the tibialis anterior muscle and the right of the gastrocnemius, phase three the right side of the tibialis anterior and gastrocnemius, phase four the left and right of the biceps femoris and the right side of the rectus femoris. In the first and second phase the shank muscles were used a lot, whereas in the third and fourth phase the shank and thigh muscles were used a lot showing the overall muscle activation of the lower limbs.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.117-126
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• 2018

The purpose of this study was to examine the relationship between the working posture and symptoms of musculoskeletal disorders of dental hygienists during scaling. The subjects in this study were 264 selected dental hygienists. A convergence study was implemented using questionnaire that was prepared to cover general characteristics, health care, the work of scaling, working posture and subjective musculoskeletal symptoms. As for data analysis, R 2.15.1 was employed. As a result of analyzing the collected data, the rate of good working posture during scaling stood at 29.9 percent; roughly good posture, at 37.5 percent; incorrect posture, at 32.6 percent. Regarding the area of the body in which they complained of musculoskeletal symptoms, the shoulders were 3.32-fold more mentioned than any other area(OR,3.32;95%CI, 1.58~6.98); the foot, 2.97-fold more(OR,2.97;95%CI, 1.18~7.48); the hands, 2.84-fold more(OR,2.84:95%CI, 1.35~5.98); the neck, 2.82-fold more(OR, 2.82;95%CI, 1.35~5.91); the back, 2.41-fold more(OR,2.41;95%CI, 1.02~5.68). The findings of the study that demonstrate the importance of good working posture are expected to make a contribution to the improvement of work environments, the development of efficient preventive programs and the preparation of sustained educational plans, and it's necessary in the future to make a research study by including psychosocial factors.